/*
 * Copyright 2017 ~ 2025 the original author or authors. <wanglsir@gmail.com, 983708408@qq.com>
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package com.wl4g.devops.coss.common.utils;

import java.text.DateFormat;
import java.text.ParseException;
import java.text.SimpleDateFormat;
import java.util.Date;
import java.util.Locale;
import java.util.SimpleTimeZone;

/**
 * A simple utility class for date formating.
 */
public class DateUtil {

	// RFC 822 Date Format
	private static final String RFC822_DATE_FORMAT = "EEE, dd MMM yyyy HH:mm:ss z";

	// ISO 8601 format
	private static final String ISO8601_DATE_FORMAT = "yyyy-MM-dd'T'HH:mm:ss.SSS'Z'";

	// Alternate ISO 8601 format without fractional seconds
	private static final String ALTERNATIVE_ISO8601_DATE_FORMAT = "yyyy-MM-dd'T'HH:mm:ss'Z'";

	/**
	 * Formats Date to GMT string.
	 */
	public static String formatRfc822Date(Date date) {
		return getRfc822DateFormat().format(date);
	}

	/**
	 * Parses a GMT-format string.
	 */
	public static Date parseRfc822Date(String dateString) throws ParseException {
		return getRfc822DateFormat().parse(dateString);
	}

	private static DateFormat getRfc822DateFormat() {
		SimpleDateFormat rfc822DateFormat = new SimpleDateFormat(RFC822_DATE_FORMAT, Locale.US);
		rfc822DateFormat.setTimeZone(new SimpleTimeZone(0, "GMT"));

		return rfc822DateFormat;
	}

	public static String formatIso8601Date(Date date) {
		return getIso8601DateFormat().format(date);
	}

	public static String formatAlternativeIso8601Date(Date date) {
		return getAlternativeIso8601DateFormat().format(date);
	}

	/**
	 * Parse a date string in the format of ISO 8601.
	 * 
	 * @param dateString
	 * @return
	 * @throws ParseException
	 */
	public static Date parseIso8601Date(String dateString) throws ParseException {
		try {
			return getIso8601DateFormat().parse(dateString);
		} catch (ParseException e) {
			return getAlternativeIso8601DateFormat().parse(dateString);
		}
	}

	private static DateFormat getIso8601DateFormat() {
		SimpleDateFormat df = new SimpleDateFormat(ISO8601_DATE_FORMAT, Locale.US);
		df.setTimeZone(new SimpleTimeZone(0, "GMT"));
		return df;
	}

	private static DateFormat getAlternativeIso8601DateFormat() {
		SimpleDateFormat df = new SimpleDateFormat(ALTERNATIVE_ISO8601_DATE_FORMAT, Locale.US);
		df.setTimeZone(new SimpleTimeZone(0, "GMT"));
		return df;
	}
}